hickman



Feb. 7, 1956 K. c. D. HICKMAN 2,734,023

COMPRESSION DISTILLATION METHOD AND APPARATUS 3 Sheets-Sheet 1 Filed May 26, 1953 E 4: INVENTOR.

Feb. 7, 1956 K. c. D HICKMAN 2,734,023

COMPRESSION DISTILLATION METHOD AND APPARATUS Filed May 26, 1953 v 3 Sheets-Sheet 2 Feb. 7, 1956 K. c. D. HICKMAN 2,734,023

COMPRESSION DISTILLATION METHOD AND APPARATUS Filed May 26, 1955 :5 Sheets-Sheet a IN VEN TOR. Kamila; zrz fled/Mm United States Patent CGMPRESSION DISTILLATION METHOD AND APPARATUS Kenneth C. D. Hickman, Rochester, N. 1., assignor of one-twentieth to Edward Harris, in, and nineteenfiftieths to Gray D. Dickason, both of Rochester, r Y.

Application May 26, E53, Serial No. 357,493

26 Claims.- (Ci. 202-64) T his invention relates to methods of and apparatus for compression distillation.

Compression stills in. common use generally employ a conventional boiler and a tubular condenser immersed in the boiling liquid, and the large body of distilland presents a relatively large resistance to the evolution of vapor. In addition, the undistilled residue contaminates the distilland. These stills also require frequent cleaning to remove the accumulation of precipitate from the heat exchanger surfaces.

Generally the difference in pressure between the evaporating and condensing sides of the heat exchanger is about three pounds, and the difference in temperature of the distilland and distillate is about 12 F. This difference of temperature or heat drop betweenthe evaporator and condenser is referred to as dt. The totalprocess of evaporation and condensation has been described by Langmuir et al. as occurring in a number of readily recognizable steps, each of which is assigned a resistance. These resistances are reciprocals of rates of process and are additive arithmetically, the total resistance R thus being the sum of r r r r. Each resistance r is associated with a temperature drop t or cit. Such resistances comprise a resistance r to the flow of vapor through the conduits, a resistance r to the how of heat through the evaporating liquid, a resistance r to the how of heat through the heat exchange barrier, a resistance r to the flow of heat through the distillate, and a resistance r to the detachment of vapor from the surface of the evaporating liquid.

While compression stills employing gravity falling films on the heat exchange surfaces have been suggested, they have not so far as I know significantly increased the efficiency of this type of still, and the heat pressure drop dt is still much greater than intrinsically required.

This necessitates the use of positive displacement pumps i or expansive turbo compressors.

I have found that by diminishing the body of distilland and/or distillate to nearly the vanishing point, so that the obstructive film is substantially lessened, resistances r r and r are greatly diminished and both the heat drop and pressure drop can be limited so materially as to create a new and useful compression distillation method and apparatus which are substantially more eliicient than those heretofore contemplated.

A principal object of this invention, therefore, is to provide a new and highly efficient compression distillation method and apparatus in which the resistance to the flow of heat through the evaporating and/or condensing films, and the resistance to separation of the vapor from the distilland are greatly reduced.

Gther and further objects of the invention will be apparent from the following description and claims and may be understood by reference to the accompanying drawings, of which there are three sheets, which by way of illustration show preferred embodiments of the invention and what l now consider to be the best; mode in which I have contemplated applying the principles of 2,734,023 Fatented Feb. 7, 1956 ice my invention. Other embodiments of the invention may be used without departing from the scope of the present invention as set forth in the appended claims.

In the drawings:

Fig. 1 is a schematic sectional view of a compression still embodying the invention and utilizing a rotary disk type of heat exchange and phase separation barrier;

Fig. 2 is a fragmentary sectional view on the line 2-2 of Fig. 1;

Fig. 3 is a view similar to Fig. 1 but showing a medi lied type of compression stage;

Fig. 4 is a view similar to Fig. l of a modified form of the invention and employing a tubular type of heat exchange and phase separation barrier;

Fig. 5 is a schematic sectional view of a compression still illustrating a modified form of the invention employ} ing heat exchange and phase separation barriers in the form of paired conical members;

Fig. 6' is a schematic view of a further modified form of the invention employing a rotary heat exchange and phase separation barrier in the form of a convoluted tubular member;

Fig. 7 is a sectional view taken along line Fig. 6;-

Fig. 8 is a modification of Fig. 6 in which the discharge of distilland on to the evaporating surface is employed to effect the rotation of the heat exchange barrier; and p Fig. 9 is a sectional view taken along the line 9- -9 of Fig. 8'.

As illustrated in' Figs. 1 and 2, a compression still embodying my invention comprises in general a rotary phase separation barrier of high thermal conductivity forming a heat exchanger, a distilland feed pipe 22, a vapor compresser 24, a discharge conduit 26 for the distillate, and a discharge conduit 28 for the undistilled residue.

The barrier 20 as illustrated comprises a disk-shaped conical element, the hub 30 of which is mounted on a drive shaft 32 for rotation therewith, the drive shaft 32 being journaled in bearing 34. A heat insulated casing 36 encloses the barrier 20 and forms on one side of the disk 20 an evaporating chamber or evaporator 38. The heat exchange surface 40 of the disk 20 ex osed to the pos'ite face 42 of thedisk or barrier 20 forms a condensing surface. The outer periphery of the disk 20 is made in the form of an annular trough or gutter 44' for collecting the undistilled or concentrated residue, and the end 46 of the discharge" conduit 28 extends into said trough 44 and opens upstream so that upon rotation of the disk liquid contained in the trough 44 will be discharged through the conduit 28. Thedistilland feed pipe 22 as illustrated terminates adjacent the center of the evaporating surface 40 on the disk 20' and forms part of a means for continuously supplying and spreading and flowing distilland on the evaporating surface 40. Rotation of the barrier 20' at a sufiicient speed will spread and flow distilland on the evaporating surface 40 ina film substantially thinner than can be secured by' a flow of such distilland of the same throughput on the same'su'rface under the influence of gravity alone. I contemplate rotating the barrier 20 at a speed such that the flowing film of distilland will be no thicker than a flow of such distilland of the same throughput on the same surface under the infiuence of a force at least ten times gravity, although satisfactory results may in some cases be obtained by employin'g slower speeds.

A brush 48 may be mounted in the chamber 38 so that the'bristles' thereof may. engage or scrub the evaporating surface 40' upon the rotation of the disk 20, and suitable provisions (not shown) may be employed for moving the" an bristles of the brush 48 into and out of contact with the surface 40. The brush 48 may optionally be utilized to dislodge precipitates, if any, from the surface 40. The casing 36 as illustrated is of cylindrical form and includes an integral back wall carrying the bearing 34 and a removable front cover 50.

The disk 29 has afiixed thereto for rotation therewith an annular wall 52 having an opening 54 in its center and integrally connected at its periphery by an annular wall 56 with the periphery of the disk 20. The condensing surface 42 of the disk, together with the peripheral wall 56 and the annular wall 52, form a condensing chamber 58 which is supplied with compressed vapor through the opening 54. The vapor compressor 24 which, as illustrated, comprises a series of blades 6%) distributed about the periphery of the disk 20 and mounted thereon for rotation therewith, serves to withdraw vapor evolved by the flowing film of distilland on the evaporating surface 40 and to compress said vapor so that it will condense at a temperature above that at which it is evolved. The compressor blades 60 discharge such vapor through a series of volute blades 62 fixed on the periphery and back wall of the casing 36 and into a space 64 between the back wall of the casing and a partition 66 supported in spaced relation thereto by blades 62 and struts 68. The partition 66 is disposed closely adjacent to the wall 52 of the barrier and has an edge defining a central opening in line with the opening 54 in the wall 52. A running seal (not shown) is provided between the wall 52 and the partition 66 so as to separate the evaporator and condenser sides of the still.

- The distillate discharge pipe 26 extends into the condenser chamber 58 and into close proximity with the inner surface of the peripheral wall 56, and has its end turned upstream so that condensed distillate will be discharged through the conduit 26. If necessary or if desired, conduits 26 and 23 may be arranged in heat exchange relation with the distilland feed pipe 22 so as to transfer heat from the concentrate and distillate to the distilland.

The shape of the condensing surface 42 separates condensate therefrom as it condenses so as to prevent the accumulation of condensate thereon, and the film of condensate will be thinner than can be secured by a flow of such condensate of the same throughput on the same surface under the influence of gravity alone, and in any event will be of a thickness of the same order of thickness as that of the distilland on the evaporating surface 40. The rotation of the condensing surface 42, will, in addition to centrifuging therefrom the condensate, also serve to further compress by centrifugal force the compressed vapor in the chamber 58 to promote the condensation thereof.

The compressed vapor is discharged by the compressor into intimate heat exchange relation with the coudensing side of the barrier and opposite the flowing film of distilland on the evaporating surface 4-0 so that the heat of condensation of the vapor on the condensing surface 42 will be transferred through the disk 20 and will promote the evolution of vapor from the flowing film on the evaporating side of the barrier. The rotation of the disk 20 at the speeds contemplated will also function to centrifuge the vapor as it evolves with respect to the flowing film on the surface 40. By greatly reducing the thickness of the films of distilland and distillate in accordance with my invention, the resistances r and r to the flow of heat through such films and the resistance r to the detachment of vapor from the surface of the evaporating liquid will be greatly diminished as compared with known systems, thereby making possible a great increase in the cflieiency of this compression distillation system.

In a preferred method of operaton, a partial vacuum equal to the saturated pressure of distilland is maintained in the still by a pump (not shown), and the distillate and residue may in addition be withdrawn by suction pumps connected to the pipes 26 and 28, in which event the heat 4 exchanger between the liquid in the pipes 26, 28 and 22 may be dispensed with.

In operation, distilland supplied through the pipe 22 to the center of the rotating evaporating surface 40 will spread and flow in a thin film of the character heretofore referred to outwardly over the surface 4% and toward the gutter 44 where the undistilled residue will be collected and discharged through the pipe 28.

It will be appreciated that the rotational speeds required to give adequate spreading of the distilland are much less than those desired for accelerating and compressing the vapor. It is contemplated therefore that the compressor means comprising the fan blades 60 may be separated from the rotating barrier, as shown in Fig. 3 where the shaft 32 rotates slowly, for instance, at 500 R. P. M. In this modification the compressor comprises a frame or disk 146 carrying fan blades 147 and mounted on a second shaft 148 rotating in a bearing 149 on the casing cover 150. The double walled barrier and associated conductors are the same in this modification, but a stationary partition 151 is supported in the casing 136 and provided with a peripheral flange 152 which extends adjacent the compressor blades 147 to form a passageway 153 leading as before into the space between the barrier walls. In this construction the compressor shaft 148 may be rotated at say 3600 R. P. M. so as to increase the compressing function. The construction and operation of this modification are otherwise as previously described.

In the modification shown in Fig. 4, the barrier is of generally conical shape, and I contemplate that the apex angle of the cone may vary within wide limits from almost to almost 0, and in the latter event the barrier would be more tubular than as illustrated in Fig. 4. In Fig. 4 the barrier comprises a thin outer concave wall 254 of high thermal conductivity and a connected wall 255 supported therefrom as shown to leave a condensing chamber 256 therebetween, the barrier being fixed on the outer end of a shaft 257 rotatably supported in a bearing 258 extending through the outlet conduit 259 of a compressor or compressor fan 266 of any known or suitable construction having its intake 261 communicating with the interior of the casing 250 as shown. The outlet conduit 259 of the compressor communicates with the chamber 256 and has a running seal with the wall 255 so as to separate the condensing chamber 256 from the evaporating chamber 252 in which the barrier rotates.

The compressor 266 withdraws vapor from the interior of the casing 250, compresses the same, and discharges it into the condensing chamber 256. A conductor 263 for distillate has an angularly turned end located in the peripheral portion of the space 256 and is led outwardly through the conduit 259 and thence to a vacuum withdrawal pump and/0r heat exchange unit (not shown). Distilland fed through the feed pipe 264 is discharged adjacent the center of the barrier wall 254 and distributed thereover by centrifugal force upon rotation of the barrier by the shaft 257. The thickness of the film of distilland on the evaporating surface of the barrier 254 will, of course, depend upon the rate of feed and the speed of rotation of the barrier, and in order to utilize the invention herein disclosed it is desirable that the barrier be rotated at a speed so that the distilland will flow in a film substantially thinner than can be secured by a flow of such distilland of the same throughput on the same surface under the influence of gravity alone, and as described in connection with the previous modification.

The undistilled residue is slung off the outer periphery of the barrier into the casing 254) and withdrawn, if desired, under suction through a conduit 266. Conduit 266 may, if desired, be passed along with the distillate 263 in heat exchange relation with the distilland feed pipe 264. The construction and operation of the modiassigned 5 fication shown in Fig. 4 are otherwise the same as those of the modifications previously described.

In the foregoing modifications the evaporating surface and the uncompressed vapor are directly exposed to the outer casing of the still, while the compressed vapor is contained within a secondary condensing chamber. Fig. 5 shows a modification where this situation is reversed and vapor is generated within a closed rotating vessel and passed therefrom through a compressor to the outer container where it is condensed on the outside of the rotating barrier and immediately flung therefrom, leaving only the thinnest film of distillate on the condensing surface to obstruct the flow of heat to the heat exchanger.

In Fig. 5 a casing 367 including a cover 368 encloses a pair of rotary paired cones 370. A centrifugal vapor compressor 372 and an electric motor 374 for driving the same are supported on the cover 368. The rotary paired cones 370 form a rotary phase separation barrier and heat exchanger of high thermal conductivity and at one end are rotatably supported by the bearing and seal assembly 376 and at the other end by the bearing and seal assembly 378. Distilland is supplied through a feed pipe 380 under the control of a valve 382 and through a degasser 384 and feed pipe 386 which extends through the bearing and seal assembly 376 to the nozzles 388 which discharge the distilland at the center of the rotating evaporating surfaces 390 of the barrier 370.

The barrier 370 is rotated at such a speed as to cause the distilland discharged by the nozzles 388 to spread and flow on the evaporating surfaces 390 in a film substantially as thin as can be secured by a flow of such distilland of the same throughput on the same surface under the influence of a force at least ten times gravity. The vapor evolved from the flowing film of distilland on the surfaces 390 is withdrawn through the conduit 392 by the centrifugal compressor 372 which compresses such vapor and discharges it through the conduit 394 into the casing 367. The compressed vapor is brought into intimate heat exchange relationship with the outer condensing surface of the barrier 370 and condensed thereon, the

heat of condensation thereof being transferred by the barrier to the flowing film on the evaporating surfaces 399 so as to promote the evolution of vapor therefrom.

The rotation of the barrier 37th separates condensate from the condensing surfaces so as to prevent the accumulation of condensate on the condensing surfaces in a layer thicker than can be secured by a flow of such condensate of the same throughput on the same surface under the influence of gravity alone. The condensate may be withdrawn from the casing through a pipe 3% under the influence of suction pump 394. The undistilled residue is collected in the troughs or gutters 396 and removed therefrom by the residue discharge pipes 393, the ends of which project into the troughs 396 and face upstream so that the liquid residue will be forcibly discharged through the pipes 398 which pass out through the bearing and seal assembly 376. A suction pump 4% may have its intake connected to the upper end of the degasser 394 and to the interior of the casing 367 so as to reduce the pressure therein.

The barrier 37b is connected by a spider hi2 to a rotary drive shaft 4M which passes through the bearing and seal assembly 376 where it may be connected to any suitable driving means for rotating the barrier at the desired speed. The de-gasser 384 and the casing 367 may be exhausted of residual air by the pump .69 so that the still will operate at the temperature of thedistilland supplied through the feed pipes ass.

The foregoing modifications show smooth rotating heat exchanger surfaces varying in contour from nearly fiat plates through a cone or parabola to a nearly cylindrical tube. Obviously other surfaces may be cut-- ployed which possess the characteristic of extending the area of heat exchange surface which can be accommodated in a given volume while providing spreading and 6 flowing of distilland and distillate in films substantially thinner than can be secured by gravity with the same throughput.

Another form of such an extended surface is shown in Fig. 6 where the rotary heat exchange and phase separation barrier d5tl-in constructed of convoluted sheet metal fastened hermetically between end plates 452, the same being rotatably supported upon a drive shaft 454 journaled in bearings 456 and 45% mounted on the casing 460. The casing 461} houses the barrier 45%. One of the end plates 452 is internally formed to provide a hollow peripheral gutter 462 to receive and collect undistilled residue through the holes 464 which communicate with the evaporating chamber 466, the holes 464 being located inside the tips of the convolutions of the rotary heat exchange barrier 450. A pickup tube 463 conveys residue from the gutter 462 through the bearing and seal assembly 553, to the exterior of the casing 46%.

A compressor fan 470 driven from the shaft 454 withdraws vapor from the evaporating chamber 466 inside of the barrier 450 and compresses the same, and the compressed vapor is then discharged into the casing 466 on the outside of the barrier 55% through the conduit 4'72. A feed pipe 474 extends into the casing 462' through the bearing and seal assembly 453, sprays distilland in two even longitudinally disposed sprays or sheets 476 and 473, one of such sets of spray being designed to impinge on one set of the internal surfaces of the rotary barrier 45% while the other set of sprays is designed to discharge liquid on to the other set of internal surfaces of the rotor 45%? during rotation thereof. The shaft 454 extends outside the casing 460 through the bearing and seal assembly 458 where it may be connected with any suitable driving means.

The rotary barrier 4550 is rotated at such speed so as to spread and flow the distilland on the internal evaporating surfaces thereof, and the vapor is withdrawn from the evaporating chamber 466 by the rotary fan 47% of the compressor through the conduit 4-30 which has a running seal with the barrier 450 so as to separate the evaporating chamber internally thereof from the condenser chamber externally thereof. Distillate is flung ofi' the outer surfaces of the barrier 454) into the chamber ass, and such condensate may be withdrawn from the condensing chamber in a manner previously described in the other modifications. This construction offers a rigid, inexpensive assembly of relatively large heat exchange area. Any lessening of the evenness of spreading of the distilland as compared with the previous modifications is compensated for by the larger available area of heat exchange surface.

A further modification is shown in Figs. 8 and 9 wherein the convoluted heat exchanger barrier is con-' structed with curved volutes 5% which are rotated by powerful sprays of distilland supplied by an external liquid: pump (not shown) through a pipe 592. in this case the evaporating chamber and surfaces are on the outside of the barrier Sit-t and the condensing surfaces and chamber are on the inside. The barrier SM is mounted for rotation on a shaft 566 journaled in bearings in the casing 508. A compressor 516 withdraws vapor from the evaporating chamber 532 through the conduit 514 and discharges the same into the interior of the barrier 5 04 where it condenses on the inner surfaces thereof. A condensate discharge pipe 516 is arranged to collect condensate in an annular trough formed in one or both of the end plates 518 of the barrier in the same manner as the undistilled residue is removed from the barrier as shown in Fig. 7.

The construction of Figs. 8 and 9 is very similar to that of Figs. 6 and 7 except for the manner in which the rotary heat exchange barrier is driven and for the fact that the condensing surface in Figs. 8 and 9 is on the'inside and the evaporating surface in Figs. 8 and 9 is on the outside,.whereas in Figs. 6 and 7 these surfaces are reversed.

It is contemplated that the modifications shown in Figs. 6, 7, 8 and 9 may be operated in the same way as those, previously discussed, and it is further contemplated in any of the modifications, if desired, that the condensing surface may be used as an evaporating surface and vice versa, although it is obvious that this reversal of the arrangement will not necessarily be advantageous in all cases.

The construction shown in Figs. 8 and 9 is particularly adapted for the concentration of slurries and fruit juices, since any suspended matter in the feed is flung off the vapor is produced by ebuliative boiling, splashings will be entrained and discharged from the boiler. Where, as in my invention, a relatively large area is exposed for evaporation, and ebuliative boiling is absent, entrainment is substantially quenched at its source.

As an example, actual experiments performed with a still of the kind illustrated in Fig. 4 gave the following results with sea water. In Table I the values for K in the last column represent the total heat transfer through the evaporating and condensing films and the heat transfer barrier itself.

Table 1 Pressure, Difi Distillate Temp.

ei- B. t. u. k Rgte agmg of ig? 2 eutlal, gg f g Transferred B. t. igjftfl atmos. percent barrier, cc. condense per than 2. 17 14. 7 (l 6. 0 7, 700 1, 280 l. 45 9. 8 40 3. 8 4, 780 1, 2'30 2. 42 16. 145 G. 7 18, 550 1, 980

rotor. Also, the construction is partly self-pumping as regards vapor and may be made entirely so by mechani cally driving the rotary barrier at high speed, as per Fig. 6 is desired. When the vapor is centrifuged off the outside and centrifugally compressed on the inside, as in this modification, it may in some applications be possible to dispense with the compressor 510.

In all the modifications it is necessary to supply some heat to promote the evolution of vapor initially, and to reduce thermal losses insulation may be appropriately applied to the still.

It has been calculated by the known Langmuir-Knudsen equation that the gross rate of evaporation of water at 100 C. is 97.7 litres per second per square meter of exposed liquid surface. When no steam is withdrawn, the same quantity of vapor condenses each second, and vapor and liquid are said to be in equilibrium. Suppose, now, that ,4 litre of water is withdrawn each second in the form of steam, then the equilibrium will be disturbed by 1 part in 1000. The evaporating vapor pressure will be 760 mm. Hg and the condensing pressure 759.24 mm. The difference in boiling points corresponding with these two pressures is less than 2/ 100 C. If we allow 2 C. as temperature drop through the separating wall and liquid films in the stills of this invention, as their thinness and extended area permit us to do, the total temperature difieronce at the rate cited is less than 2.1 C.

The more useful situation, however, is when a relatively strong salt solution is evaporated and the steam is r condensed to substantially pure water. As a useful simplification, it will be considered that the dissolved solids of sea water lower the vapor pressure of steam at 100 by 4.3 mm. for each 1% dissolved. To concentrate sea water from approximately 3% salt to salt will require a minimum pressure difference between evaporator and condenser of +2 mm. Hg, or 36 of water, or 1.7 lbs. gauge. At the other extreme, brackish water containing /2 of 1% of solids will require 2.2+2.1=4.3 mm. Hg, or 2.33 inches of water pressure difference. The construction according to my invention, while embodying real economies of first cost and low pressure differential for the distillation of heavy salt solutions, shows its greatest relative economy in purifying brackish waters of moderate salt content. The pressure differences required by other compression stills are much greater because of the construction of still and the difficulty of detaching vapor from the surface of the distilland.

in a compression still there are thus two drops in pressure to be considered, one due to the intrinsic difference in vapor pressure of pure water and concentrated salt solution, the other due to difficulty of detaching vapor from the distilland. Where high pressure differentials are used, as in connection with conventional boilers, high velocities of vapor are automatically involved, and, if the The figures for K are thus seen to be better than the very best hitherto known in steam boiler and condenser practice, and the temperature differentials are lower than reported in existing compression distillation of sea water at reasonable throughputs. This new, useful and remarlo able result has not heretofore been realized with thin film compression stills utilizing stationary or slowly rotating barriers.

The compression still, according to my invention, is particularly useful in connection with the purification of water, such as brackish water and sea water. There are, however, many other impure liquids which are distilled in large volume and where the cost of heat for distillation is a major item, and I contemplate the use of the various forms of still embodying my invention for the distillation generally of organic substances, including particularly petroleum distillates, alcohols, ethers and esters, which are manufactured and handled in large quantities by industry. I do not, however, limit the use of my invention to these substances and contemplate purification of any mixtures of liquid material where the use of extended surfaces lowers thermal exposure and Where substantial conservation of vapors is important.

It is to be understood that the vapor should be compressed to an extent sufficient so that it will condense at a temperature on the condensing surface just above that at which vapor is evolved from the film of distilland on the opposite side of the barrier, and preferably the vapor is compressed to create a pressure differential of less than 20% of the absolute saturated vapor pressure of the distilland at the temperature of the film thereof.

it will thus be seen that the invention accomplishes its objects and while it has been herein disclosed by reference to the details of preferred embodiments, it is to be understood that such disclosure is intended in an illustrative, rather than a limiting sense, as it is contemplated that various modifications in the method steps and their order and in the construction and arrangement of the parts, will readily occur to those skilled in the art, Within the spirit of the invention and the scope of the appended claims.

This application is a CQIlllllllZlllOIl-llbptlft of application Serial No. 295.246 filed lane 24, 1952, now abandoned.

1 claim:

1. in a compression still, at least one rotary heat exchange and phase separation barrier of high thermal conductivity having integral evaporating and condensing surfaces disposed in heat exchange relation and so that upon the rotation thereof centrifugal force will be applied to liquid disposed on said surfaces, means for continuously supplying distilland to said evaporating surface on one side of said exchanger at a rate in excess of that required to wet said evaporating surface, said evaporating surface being arranged so that upon rotation thereof such dis- 9 tilland will be free to spread and flow on such surface under the forces applied to such distilland, means for rotating said barrier at a speed sufiicient: to continuously spread and flow distilland on said evaporating surface in a film substantially thinner than that which can be secured by a flow of such distilland of the same throughput on the same surface under the influence of gravity alone; to maintain the distilland on said evaporating surface continuously under forces many times greater than gravity; and to centrifugally discharge the residue from said evaporating surface of said barrier, means for withdrawing vapor evolved by such flowing film of distilland and compressing said vapor so that it will condense at a temperature above that at which it evolved, means for directing said compressed vapor into intimate heat exchange relation with the condensing surface on the other side of said rotating barrier so as to condense said compressed vapor on said condensing surface and to transfer the heat of condensation thereof to said flowing film on said evaporatin surface, to effect the evolution of vapor therefrom, said barrier being constructed so that such rotation thereof separates siich condensate from said condensing surface as itc'ondenses thereon so as to prevent the accumulation of condensate thereon and to maintain such condensate on said condensing surface in a film subst-antially' thinner than a film of such condensate of the samethroughput on the same surface flowing under the influenceof gravity alone.

2. A compression still according to claim I wherein said means. rotate said barrier at such a speed that said flowing fil'rn of distilland will be no thicker than a flow of such distilland of the same throughput on the same surface under the influence of a force at least ten times gravity.

,3. A compression still according to claim 1 wherein said barrier comprises a disk.

4. A compression sun, according to claim 1 wherein said barrier comprises a conical member.

SQA compression still according to claim 1 wherein said barrier comprises a tubular member.

6. A- cornpression still according to claim 1 wherein said barrier comprises a convoluted tubular member.

7 A compression still according to claim 1 wherein said barrier comprises paired conical members forming a closed compartment therebetween.

3.- A compression still according to claim 1 wherein said barrier isin the form of a hollow member, the inside of which forms the evaporating surface and the outside of which forms the condensing surface.

9. A compression still according to claim 1 wherein said barrier is in the form of a hollow member, the inside of which forms the condensing surface and the outside of which forms-the evaporating surface.

10. A compression still according to claim 1 wherein said compres ing. means are constructed and, arranged to compres said vapor so as to create a pressure differential of less than of the absolute saturated vapor pressure of the distilland at the temperature thereof.

11'. A compression still according to claim 1 including provisions for centrifuging said vapor as it evolves with respect to said film.

12 A compression still according to claim 1 wherein said vapor compressing means comprises an axial comresser.

13. A compression still according to claim 1 wherein said vapor compressing means comprises a centrifugal compressor.

14. In a compression still, at least one heat exchange and phase separation barrier of high thermal conductivity haiiing' integral evaporating and condensing surfaces disposed in heat eXchange relation, means for continuously supplying distilland to said evaporating surface at a fate in excess of that required to wet said evaporating surface, said evaporating suffaee being arranged so that such distilland is free to spread and flow on such evaporating surface, means for applying forceof a magnitude many times in excess of gravity to such distilland so as.

to spread and flow such distilland on said evaporating surface in a film substantially thinner than that which can be secured by a flow of such distilland of the same throughput on the same surface flowing under the influence of gravity alone thereby to substantially reduce the resistance to evolution of vapor from said distilland and forcibly discharge the residue from said evaporating surface, means for withdrawing vapor evolved by such flowing film of distilland and compressing saidvapor so that it will condense at a temperature above that at which it evolved, means for directing said compressed vapor into intimate heat exchange relation with said condensing surface so as to condense said compressed vapor on said condensing surface and to transfer the heat of condensation thereof to said flowing film on said evaporating surface to effect the evolution of vapor therefrom, and means for separating such condensate from said condensing surface as it condenses thereon so as to prevent the accumulation of condensate thereon and to maintain said condensate on said condensing surface in a film substantially thinner than a film of such condensate of the same throughput on the same surface flowing under the influence of gravity alone.

15. A compression still according to claim 14 wherein means are provided for rotating such barrier at a speed such that said flowing film of distilland will be no thicker than a flow of such distilland at the same throughput on the same surface under the influence of a force at least ten times gravity.

l6. Acornpression still according to claim 14 wherein distilland discharged by said distilland supplying and spreading means is utilized to effect the rotation of said barrier.

l7. In a compression still, at least one rotary phase separation and heat exchange barrier of high thermal conductivity having integral evaporating and condensing surfaces disposed in heat exchange relation, said evaporating surface being so disposed that liquid thereon will be forced against and caused to spread and flow over said evaporating surface due to the rotation of said barrier, means for continuously applying distilland to said evaporating surface at a rate in excess of that required to wet said surface at the speed at which said barrier is rotated, means for rotating said barrier at a speed sufficient to continuously apply to said distilland force of a magnitude many times in excess of the force of gravity acting on said distilland, so as to spread and how such distilland continuously on said surface in a film substantially thinner than that which can be secured by a flow of such. distilland of the same throughput on the same surface under the influence of gravity alone and so that said distilland is forced against said evaporating surface in addition to spreading and flowing thereon, means for Withdrawing vapor evolved by such flowing film of distilland and compressing said vapor so that it will condense ata temperature above that at which it evolved, said barrier being rotated at such speed as to centrifugally discharge the residue from said evaporating surface, means for directing said compressed vapor into intimate heat exchange relation with said condensing surface so as to condense said compressed vapor on said condensing surface and to transfer the heat of condensation thereof to said flowing film onv said evaporating surface to effect the evolution of vapor therefrom, said condensing surface being so disposed with respect to the axis of rotation of said barrier that centrifugal force applied to condensate on said condensing surface, due to such rotation of said barrier, will centrifugally remove such condensate from such condensing surface as it condenses thereon to prevent the accumulation of condensate on said condensing surface and so as to maintain such condensate on said condensing surface in a film substantially thinner than a film of such condensate of the same vatars 1 1 throughput on the same surface flowing under the influence of gravity alone.

18. In a compression still, at least one rotary phase separation barrier and heat exchanger of high thermal conductivity having an integral evaporating surface on one side and a condensing surface on the opposite side, an annular collecting trough so disposed with respect to said evaporating surface as to collect and confine liquid centrifugally discharged therefrom and to prevent dispersion of said liquid in the form of a spray, means for continuously applying distilland to said evaporating surface at a rate in excess of that required to wet said evaporating surface, said evaporating surface being arranged so that upon rotation thereof such distilland will be free to spread and flow on such evaporating surface under the force applied thereto due to rotation of said barrier, means for rotating said barrier at a speed sufficient to continuously apply to said distilland on said evaporating surface, centrifugal force of a magnitude many times in excess of the force of gravity acting on said distilland on said evaporating surface, so as to spread and flow such distilland continuously on said evaporating surface in a film substantially thinner than that which can be secured by a flow of such distilland of the same throughput on the same surface under the influence of gravity alone, means for withdrawing vapor evolved by such flowing film of distilland and compressing said vapor so that it will condense at a temperature above that at which it evolved, said barrier rotating means being constructed and arranged so that such rotation of said barrier is effective to centrifugally discharge the residue from said evaporating surface into the said collecting trough thereby to separate the residue from said distilland, said evaporating surface and the vapor evolved therefrom, means for directing said compressed vapor into intimate heat exchange relation with said condensing surface so as to condense said compressed vapor on said condensing surface and to transfer the heat of condensation thereof to said flowing film on said evaporating sur face to effect the evolution of vapor therefrom, said barrier being constructed so that such rotation thereof separates condensate from said condensing surface as it condenses thereon thereby to prevent the accumulation of condensate thereon and so as to maintain such condensate on said condensing surface in a film substantially thinner than a film of such condensate of the same throughput on the same surface flowing under the influence of gravity alone, and a conduit having its end projecting into said trough for discharging residue therefrom.

19. in a compression still, at least one rotary phase separation barrier and heat exchanger of high thermal conductivity having an integral evaporating surface on one side and a condensing surface on the opposite side, a collecting trough so disposed with respect to said evaporating surface as to collect and confine liquid discharged therefrom and to prevent dispersion of said liquid in the form of a spray, means for continuously applying distilland to said evaporating surface at a rate in excess of that required to wet said evaporating surface, said evaporating surface being arranged so that such distilland will be free to spread and flow on such evaporating surface under the force applied thereto upon rotation of said barrier, means for rotating said barrier at a speed suflicient to continuously apply to said distilland on said evaporating surface, centrifugal force of a magni tude many times in excess of the force of gravity acting on said distilland on said evaporating surface, so as to spread and flow such distilland continuously on said evaporating surface in a film substantially thinner than that which can be secured by flow of such distilland of the same throughput on the same surface flowing under the influence of gravity alone, and so as continuously to discharge the residue from said evaporating surface into said collecting trough thereby to separate the residue from the distilland, said evaporating surface and the vapor evolved therefrom, means for withdrawing vapor evolved by such flowing film of distilland and compressing said vapor so that it will condense at a temperature above that at which it evolved, means for directing said compressed vapor into intimate heat exchange relation with said condensing surface so as to condense said compressed vapor on said condensing surface and to transfer the heat of condensation thereof to said flowing film on said evaporating surface to effect the evolution of vapor therefrom, said barrier being constructed so that such rotation is effective to fling condensate from said condensing surface as it condenses thereon.

20. That method of continuous distillation which comprises rotating a heat exchanger at a speed sufficient to apply centrifugal force of a magnitude many times greater the. t the force of gravity to distilland so as to continuously distribute and flow and maintain distilland on the evaporating surface of said heat exchanger in a film substantially thinner than can be secured by a flowof such distilland of the same throughput on the same surface flowing under the influence of a force of the order of gravity alone, continuously evolving vapor from said flowing film while continuously separating the residue therefrom, collecting said residue out of contact with said flowing film, withdrawing and compressing said vapor and contacting such compressed vapor with a condensing surface on the opposite side of said heat exchanger so as to condense said vapor thereon, transferriru the heat absorbed by the heat exchanger, due to the condensation of vapor on the condensing surface thereof, to said evaporating surface and thence to said film of distilland to effect the evolution of vapor therefrom, and utilizing the rotation of said heat exchanger to separate condensate from said condensing surface as it condenses thereon so as to prevent the accumulation of condensate on said condensing surface.

2i. That method according to claim 20 wherein the vapor is compressed to create a pressure differential of less than 20% of the absolute saturated vapor pressure of the distilland at the temperature thereof.

22. That method according to claim 20 including the step of centrifuging said vapor as it evolves with respect to said evaporating face.

23. That method of continuous distillation which comprises applying force of a magnitude many times greater than the force of gravity to distilland, so as to continuously distribute and flow distilland on the evaporating surface of a heat exchanger in a film substantially thinner than can be secured by a flow of such distilland of the same throughput on the same surface flowing under the influence of a force of the order of gravity alone, thereby reducing the resistance to evolution of vapor from said film, continuously evolving vapor from said flowing film while removing the residue therefrom andtfrom contact with said surface, collecting said residue out of contact with said flowing film and out of the path of vapor evolving therefrom, withdrawing and compressing said vapor and contacting such compressed vapor with a condensing surface on the opposite side of said heat exchanger so as to condense said vapor thereon, transferring the heat absorbed by the heat exchanger, due to the condensation of vapor on the condensing surface thereof, to said evaporating surface and thence to said film of distilland to efifect the evolution of vapor therefrom, and applying force many times greater than the force of gravity to said condensate as it condenses on said condensing surface so as to fling condensate therefrom and thereby maintain such condensate on said condensing surface in a film substantially thinner than a film of such condensate of the same throughput on the same surface flowing under the influence of gravity alone.

24. That method of continuous distillation which comprises applying centrifugal force of a magnitude many a times greater than the force of gravity to distilland, so as to continuously distribute and flow distilland on the evaporating surface of aheat exchanger in a film substantially thinner than can be secured by a flow of such distilland of the same throughput on the same surface under the influence of a force of the Order of gravity alone, applying centrifugal force to such distilland for holding it against such evaporating surface, continuously evolving vapor from said flowing film while removing the residue therefrom and from contact with said surface, withdrawing and compressing said vapor and contacting the compressed vapor with a condensing surface on the opposite side of said heat exchanger so as to condense said vapor thereon, transferring the heat absorbed by the heat exchanger, due to the condensation of vapor on the condensing surface thereof, to said evaporating surface and thence to said film of distilland to effect the evolution of vapor therefrom, and applying centrifugal force many times greater than the force of gravity to said condensate as it condenses on said condensing surface, so as to prevent the accumulation of such condensate on such condensing surface in a film thicker than that of said flowing film of distilland and so as to fling such condensate away from such condensing surface. 7

25. That method pertaining to the transfer of heat through a heat exchanger for evolving vapor from a flowing film of liquid on one side of said exchanger, by the heat of its own vapor, raised in temperature by compression and condensed on the opposite side of said exchanger, which comprises continuously applying centrifugal force of at least ten times gravity to the liquid on said one side 14 of said exchanger and to the distillate formed by said vapor as it condenses on said opposite side of said heat exchanger so as to maintain each of said liquids in a film on said heat exchanger substantially thinner than a film of the same liquid of the same throughput flowing on the same surface under the influence of gravity alone.

26. That method pertaining to the transfer of heat through a heat exchange and phase separation barrier to a flowing film of distilland on one side of said exchanger, from the heat liberated upon the condensation of vapor therefrom raised in temperature by compression and condensed on the opposite side of said exchanger, which comprises rotating said exchanger at such a speed as to apply centrifugal force of at least ten times gravity to said liquids so as to maintain each of the same in a film on said barrier substantially thinner than a film of the same liquid of the same throughput flowing on the same surface under the influence of gravity alone.

References Cited in the file of this patent UNITED STATES PATENTS 1,501,515 Testrup July 15, 1924 2,210,927 Hickman Aug. 13, 1940 2,218,240 Hickman Oct. 15, 1940 2,308,008 Hickman Jan. 12, 1943 2,554,703 Hickman May 29, 1951 2,566,274 White et al. Aug. 28, 1951 2,703,310 Kretchmar Mar. 1, 1955 

26. THAT METHOD PERTAINING TO THE TRANSFER OF HEAT THROUGH A HEAT EXCHANGE AND PHASE SEPARATION BARRIER TO A FLOWING FILM OF DISTILLAND ON ONE SIDE OF SAID EXCHANGER, FROM THE HEAT LIBERATED UPON THE CONDENSATION OF VAPOR THEREFROM RAISED IN TEMPERATURE BY COMPRESSION AND CONDENSED ON THE OPPOSITE SIDE OF SAID EXCHANGER, WHICH COMPRISES ROTATING SAID EXCHANGER AT SUCH A SPEED AS TO APPLY CENTRIFUGAL FORCE OF AT LEAST TEN TIMES GRAVITY TO SAID LIQUIDS SO AS TO MAINTAIN EACH OF THE SAME IN A 